Recently, various input terminals which can detect pressing force information have been proposed. An input terminal which can detect pressing force information is, for example, an input terminal which is mounted on a surface of a display, and which a user can input pressing force information on a flat surface by directly touching the input terminal with his finger or by touching the input terminal using a dedicated instrument.
As a technique relating to such an input terminal, patent document 1 discloses an input terminal having a structure where an operation surface is formed by laminating a piezoelectric film to a holding member (formed of an acrylic cover, a glass cover or the like), and an outer peripheral edge of the operation surface is adhered to a casing. Such a piezoelectric film is formed using an L-type polylactic acid (PLLA) which is uniaxially stretched so as not to be influenced by pyroelectricity. With such a configuration, the input terminal can detect pressing force information based on a voltage (charge) generated due to strain in the piezoelectric film when a pressing operation is performed on the operation surface.
Patent Document 1: Japanese Patent Application Laid-Open No. 2013-242900